The invention relates generally to a digital logic system for controlled sequencing of a stepper motor and more particularly for controlling the tilt position of a print head in a high speed printer.
While stepper motors have been used in a variety of devices, including printing devices, the dichotomy of optimizing the stepper motor speed and yet at the same time effectively damp the servo motor at the final position has remained a problem that until the present invention could not be solved without complicated and expensive feedback means from the step motor to the motor control in a closed-loop servo system. Examples of a closed-loop servo mechanisms for electronically damping a servo motor as it approaches its final position are disclosed in U.S. Pat. Nos. 3,573,589 and 3,760,252 of common ownership herewith.
In the past the tilt position of a print head has been controlled by a mechanical decoder which mechanically controlled the direction and degree of rotation of a print head in accordance with information received by a pair of solenoids which were energized in accordance with the desired tilt position of the print head for the character to be printed. The overall print speed of the printer was limited to the speed in which the various mechanisms employed in the mechanical decoder could be actuated. Furthermore, these mechanisms in the mechanical decoder were expensive to fabricate, noisy in operation and required a great deal of maintenance.